// Copyright 2010-2018 Google LLC
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.


// [START program]
using System;
using Google.OrTools.Sat;

// [START solution_printing]
public class VarArraySolutionPrinter : CpSolverSolutionCallback
{
  public VarArraySolutionPrinter(IntVar[] variables)
  {
    variables_ = variables;
  }

  public override void OnSolutionCallback()
  {
    {
      foreach (IntVar v in variables_)
      {
        Console.Write(
            String.Format("  {0}={1}", v.ShortString(), Value(v)));
      }
      Console.WriteLine();
      solution_count_++;
    }
  }

  public int SolutionCount()
  {
    return solution_count_;
  }

  private int solution_count_;
  private IntVar[] variables_;
}
// [END solution_printing]

public class CpIsFunSat
{
  // Solve the CP+IS+FUN==TRUE cryptarithm.
  static void Main()
  {
    // Constraint programming engine
    CpModel model = new CpModel();

    // [START variables]
    int kBase = 10;

    IntVar c = model.NewIntVar(1, kBase - 1, "C");
    IntVar p = model.NewIntVar(0, kBase - 1, "P");
    IntVar i = model.NewIntVar(1, kBase - 1, "I");
    IntVar s = model.NewIntVar(0, kBase - 1, "S");
    IntVar f = model.NewIntVar(1, kBase - 1, "F");
    IntVar u = model.NewIntVar(0, kBase - 1, "U");
    IntVar n = model.NewIntVar(0, kBase - 1, "N");
    IntVar t = model.NewIntVar(1, kBase - 1, "T");
    IntVar r = model.NewIntVar(0, kBase - 1, "R");
    IntVar e = model.NewIntVar(0, kBase - 1, "E");

    // We need to group variables in a list to use the constraint AllDifferent.
    IntVar[] letters = new IntVar[] {c, p, i, s, f, u, n, t, r, e};
    // [END variables]

    // [START constraints]
    // Define constraints.
    model.AddAllDifferent(letters);

    // CP + IS + FUN = TRUE
    model.Add(c * kBase + p + i * kBase + s + f * kBase * kBase + u * kBase + n ==
              t * kBase * kBase * kBase + r * kBase * kBase + u * kBase + e);
    // [END constraints]

    // [START solve]
    // Creates a solver and solves the model.
    CpSolver solver = new CpSolver();
    VarArraySolutionPrinter cb = new VarArraySolutionPrinter(letters);
    solver.SearchAllSolutions(model, cb);
    // [END solve]

    Console.WriteLine("Statistics");
    Console.WriteLine($"  - conflicts : {solver.NumConflicts()}");
    Console.WriteLine($"  - branches  : {solver.NumBranches()}");
    Console.WriteLine($"  - wall time : {solver.WallTime()} s");
    Console.WriteLine($"  - number of solutions found: {cb.SolutionCount()}");
  }
}
// [END program]